The invention relates to a veterinary syringe, comprising a base body, on the front side of which a syringe barrel receiving the medicament is arranged while a guiding element for a plunger rod that is guided therein so as to be movable in a longitudinal direction is arranged on the rear side thereof, and one end of said plunger rod, to which a plunger is attached, extends into the syringe barrel, said syringe further comprising a handle for holding the syringe, an operating lever, one end of which is pivotably attached to the lower part of the handle while the other end thereof is guided within the bottom side of the guiding element and engages with a toothed rack via a spring-biased catch, said toothed rack being disposed on the bottom side of the plunger rod, and a locking device for the plunger rod which engages with the toothed rack is provided as a locking slider disposed inside the guiding element so as to be movable in a vertical direction at the end thereof, is provided with an opening through which the plunger rod is guided and extends into the toothed rack from below, locking said toothed rack so as to prevent it from withdrawing, wherein said locking slider can be moved from the locked position into a released position for the toothed rack and can be maintained in said released position by means of an actuator.
Such known veterinary syringes, also referred to as repeater syringes, are used for mass vaccination of sheep, swine and cattle, and thus have to withstand high stresses. Above all, such syringes need to be insensitive to soiling, in particular with regard to the operating and adjusting elements provided on such syringe.
In such a known syringe, the locking device is also provided in the form of a locking slider, which is arranged within the guiding element for the plunger rod so as to be vertically movable, encompasses the plunger rod and extends into the toothed rack from below, under a spring load. The locking slider may be pushed down from above, against a spring force, so as to release the toothed catch and to allow retraction of the plunger rod. In order to maintain the locking slider in its pushed-in form, the known veterinary syringe has an annular lock which is arranged on the guiding element so as to be movable thereon in a longitudinal direction, in the region of the guiding element which extends between the base body and/or the handle, on the one hand, and the catch attached to the operating lever, on the other hand.
When the operating lever is in its resting position, i.e. at its greatest distance from the handle, the lock may be moved back toward the operating lever, or the catch attached thereto may be moved along the guiding element, with the lock pushing the locking slider down against the pressure of a spring, or then maintaining it in this position, respectively. In this condition, the plunger rod can be pulled back. If the syringe is operated again, i.e. if the operating lever is moved forward toward the handle, then the operating lever or the catch, respectively, pushes the lock forward, thus releasing the locking slider, which moves out of its locked position due to the spring load and releases the plunger rod, so that vaccinations can be carried out.
Providing the lock as a ring which is movable on the guiding element in a longitudinal direction has the disadvantage that it becomes increasingly difficult for said lock to slide on the guiding element due to the constant soiling of this area by the use of the syringe, which may eventually cause the syringe, or in particular, the lock and, thus, the locking device, to be no longer operable or releasable.